In general, the invention relates to methods and compositions for the generation and use of conformation-specific antibodies or fragments thereof.
Protein phosphorylation is a key cellular signaling mechanism that induces changes in protein conformation. For example, the phosphorylation of specific serine or threonine residues that immediately precede a proline residue (Ser/Thr-Pro motif) is a central regulatory mechanism in the cell. The unique stereochemistry of the proline residue means that the peptidyl-prolyl bond of the Ser/Thr-Pro motif can adopt two different conformational states (i.e., a cis conformation or a trans conformation). Peptidyl-prolyl cis/trans isomerases (PPIases) specifically catalyze the cis/trans isomerization of Ser/Thr-Pro motifs and, thus, regulate the structure of these proteins between the two distinct conformations.
Pin1 is a PPIase that specifically catalyzes the cis/trans isomerization of certain phosphorylated Ser/Thr-Pro (pSer/Thr-Pro) motifs. The identification of Pin1 as a phosphorylation-specific PPIase led to the understanding of a new signaling mechanism, whereby Pin1 catalytically regulates the conformation of its substrates after their phosphorylation to further control protein function. Indeed, Pin1-catalyzed conformational changes control many protein functions. Moreover, Pin1 is tightly regulated by multiple mechanisms, and the deregulation of Pin1 plays a pivotal role in some human diseases (e.g., cancer, Alzheimer's disease, and asthma). Given the completely different conformation of cis and trans Ser/Thr-Pro motifs (e.g., phosphorylated and nonphosphorylated Ser/Thr-Pro motifs), the generation of conformation-specific antibodies would allow for the diagnosis and treatment of disorders associated with specific protein conformations.
Thus, there exists a need in the art for conformation-specific antibodies that specifically bind to a cis or trans conformation of a Xaa-Pro (e.g., Ser/Thr-Pro or phosphorylated Ser/Thr-Pro) motif of a polypeptide, where Xaa may be any amino acid residue.